Process for devitalizing teeth using high-frequency electric current

ABSTRACT

Process for devitalizing a tooth by transmission of a high-frequency electric pulse to the vascular and nervous tissue in the root canal by insertion in said canal of an electrode in the form of a needle ( 100 ), said pulse being generated by an electronic apparatus ( 10 ), values of power, time and frequency of said electric pulse being automatically regulated by the electronic apparatus in accordance with the control given by pressing one or another of four push buttons ( 30-33 ) one for each of the different types of teeth.

The invention concerns medical equipment for dental use.

Before operating on a tooth to remove decay or for other purposes it isknown that the vascular and nerve tissue inside the canal in the root ofthe tooth concerned has to be removed.

This is done by introducing into said canal an instrument which bylateral and rotary movements can bring to the surface the materialinside it. There may be one or more canals according to the type oftooth. The operation may involve some considerable difficulty because ofcurves in canals and their divisions.

The instrument used for the purpose does not always achieve the desiredresults because of the above-mentioned anatomical characteristics. Thisoperation is long and laborious.

It also requires repeated X-ray checks to see that the work isproceeding correctly. To ensure that the canal has been devitalized itis essential not only to clean it out but also to avoid penetratingbeyond the lower end of each canal.

A certain distance, about mm 1.5, must be maintained from the apicalforamen to avoid infection and bacterial complications generally.Bearing in mind that to devitalize the canal root is a dental treatmentthat requires great precision and careful attention, dealing correctlywith the problems that arise using present methods must clearly dependon the dentist's ability.

SUMMARY OF THE INVENTION

The present invention eliminates the above drawbacks almost entirelyboth as regards the patient and the operator as will be explained below.Subject of the invention is a process to devitalize the canal root of atooth in which the vascular nervous material receives a fractionallylong high frequency electric pulse, power values, time and frequency,being adjusted to suit the type of tooth.

To carry out this procedure an electrode in the form of a needle isinserted into the canal in the root; the electrode is of a length thatallows it to penetrate until it reaches the right distance from theapical foramen and is connected to a pulse-generating apparatus.

Emission of high frequency pulses can be assisted by electricallyconnecting the electronic circuit that generates them to some other partof the patient's body, the hand for example, by a so-called neutralhandle-type metal object, or by some other suitable tool.

The effect of this high frequency pulse that acts only along the wholesurface of the needle-type electrode, is to disintegrate the vascularnerve matter and simultaneously coagulate the part of the vascularbundle that is not destroyed, as well as to sterilize the root canal.

In order to insert the needle-type electrode into the root canal,anaesthetic is applied to the area of the tooth concerned which is thenopened up till entry into the root canal is visible.

The high frequency electric pulse is preferably provided by an apparatusthat comprises an electronic circuit able to estimate the correctdistance from the apical foramen to which the needle must penetrate andto give an acoustic and visual warning as soon as that position isreached. In this way the operator can have suitable electric currentgenerated for destroying the nerve bundle in the root canal when theneedle has reached the above position.

Closure of the electric circuit is preferably pedal-operated.

Values of electric current suitable for destroying the nerve bundle inthe root are automatically regulated by the electronic apparatusaccording to which of the four buttons is pressed, these beingrespectively for the four types of teeth: incisor, canine, premolar andmolar

Value of the electric current can be increased by pressing a button forthis purpose placed on the apparatus.

The needle-type electrode, preferably of stainless steel, that transmitsthe high-frequency pulse, can be of different lengths, average mm 30,and may be of a tapering structure with a base diameter of about mm 0.25and a tip diameter of about mm 0.1.

In a preferred execution the needle has a haft, about mm 1 in diameter,comprising a rear section about mm 15 long and a front section about mm5 long set at an angle of about 110° in relation to the rear section.

The apparatus that actuates the described process comprises a cable forelectric feed, a cable for pedal control of the devitalization pulse, asocket for a cable connecting it to a so-called active handle ofinsulating material with a metal core, and can comprise a socket for thecable connecting it to the so-called neutral handle.

At the front end of said active handle is a head into which the needlecan be introduced and fixed.

The cable connected to the so-called neutral handle can includeinsertion of a branch cable to carry a kind of pincer which ispreferably applied to the lip of the patient during the measuringoperation.

The apparatus here concerned may be equipped with the following mainelectronic circuits: input filters, feeder, RF pulse generator orpulser, for setting output power, a power visualizer for setting Bursttime, for the change-over from manual to automatic functioning or viceversa, for protection against an increase in the output power setting,for safety to prevent involuntary repetition of the devitalizationmovement before a set time, for example 10 seconds, has passed, for anacoustic two-tone warning when, during the measuring operation, theneedle has penetrated to the correct distance from the apical foramenand for a single-tone sound to indicate that the devitalizing electricpulse has been given and that the operation has therefore beencompleted.

The process offers evident advantages.

Present mechanical methods involve a risk of bacteria remaining in thecanal of the root that may lead to pathological conditions of the toothor of its adjacent structure producing haemorrhage or infection.

The method described makes it possible to devitalize the root canalquickly and painlessly using very little anaesthetic which is thereforeless toxic for the patient.

After the operation the root canal is completely sterilized both in itsmain part and in its lateral branches.

Any haemorrhage or infections are entirely avoided.

The risk is also avoided of penetrating beyond the apical formen, a riskalways present with the manual instruments in use, and one that can leadto considerable complications.

To sum up these advantages, with a small low-cost easily operatedapparatus, for the first time in the field of dentistry apicalmeasurement and electronic devitalization can be done limiting theoperation exclusively to disintegration of the vascular nerve bundle.

In conclusion, this method enables both dentists and patients toundertake dental treatment in an entirely new way which offers importantadvantages, not only in time and cost but also in patient comfort,maximum reliability and elimination of errors.

Characteristics and purposes of the invention will be made still clearerby the following example of its execution illustrated withdiagrammatically drawn figures.

FIG. 1 Perspective view from above of the apparatus used to execute theinvented process.

FIG. 2 Longitudinal section of a decayed molar tooth.

FIG. 3 The tooth in FIG. 2 after opening it for access to entry to theroot canal.

FIG. 4 The tooth during measurement of depth of the root canal.

FIG. 5 The patient during measurement of depth of the root canal.

FIG. 6 The patient during the process of devitalizing the root canal.

FIG. 7 The tooth in FIG. 2 after devitalization and the canal closed.

FIG. 8 Electronic diagram of the apparatus.

FIGS. 9-11 Electronic diagram of the feeder

FIGS. 12-13 Electronic diagram of RF output and controls.

FIGS. 14-22 Electronic diagram of time selection and CLK.

FIG. 23 Electronic diagram of the RF power pulser.

FIGS. 24-26 Electronic diagram of RF output power regulation.

FIGS. 27-29 Device for delaying involuntary movements.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

The apparatus 10 comprises a substantially parallelepiped box 11, flatwith a front 12 inclined at about 45°.

Approximate dimensions of this box are mm 250×250×100.

The following controls are placed on the front of the box:

Push button 20 with pilot light 21 for turning the apparatus on and off.

Push botton 22 with pilot light 23 for passing to the measuring “mode”.

Push button 24 with pilot light 25 for manual increase of power of theelectric pulse.

Using the respective push buttons 30, 31, 32, 33, each with pilot light,the apparatus can operate suitable functional characteristics for thedifferent types of teeth: incisor, canine, premolar, molar.

Sockets 35 and 36 receive the plugs 51 and 61 respectively for theactive handle 50 and the neutral handle 60.

At the back of the apparatus, not seen in FIG. 1, there is a socket forplug 71 for working the pedal 70.

Electric feed is supplied through the plug 80. The active handle 50 ismade of insulating material and includes an electrically conductingmetal core 53 for contact with the metal needles. Said metal core isconnected internally to the plug 51 through the wire 54.

Length of said handle is substantially mm 100, with a diameter of mm 12in the head 52 into which can be inserted the haft 101 of the needle 100as seen in FIG. 4

An assortment of needles is provided comprising various lengths, but theaverage length is about mm 30.

Their shape is tapered, diameter varying from about mm 0.25 at the baseto about mm 0.1 at the tip (FIG. 4).

The needles are made of stainless steel.

Diameter of the haft 101 for the needles is about mm 1, length of therear section 102 being about mm 15 and that of the front section 103about mm 5.

The fore end is bent at an angle of about 110° compared with the rear.The active handle can be assisted by electric connection to theelectronic circuit, that generates the high frequency pulses, withanother part of the patient's body, the hand for example, by means of aso-called neutral handle 60.

Length of said neutral handle is about mm 100, diameter about mm 25; itis made of electrically conducting metal and is connected by the cable62 to the plug 61.

There is a branch line 65 from said cable 62 to connect with anelectrically conducting pincer 64 that can be fixed to a sensitive partof the human body, especially to the lip.

By means of the pedal 70 and electric cable 72 that connects to the plug71, the devitalizing electric pulse can be controlled by the foot. Todevitalize the root canal properly, it is necessary to penetrate closeto the apical point but to avoid going beyond it.

FIGS. 2 and 3 show in perspective, a cross section of a premolar 80 withits crown 81, dentine 82, pulp 83, root canals 84, 85, bundle of nerves40, artery 41 and vein 42.

These canals have an anatomical apex 90 and a radiological apex 91. Itis known that devitalization must be done close to the anatomical apex90 but must not go beyond it, so that the length of the root canal mustbe measured from the top 93 of the tooth down to the anatomical apex 90,tooth by tooth.

These measurements are obviously necessary because of the great varietyof tooth sizes among types of person, age and other factors. The needle100 already described permits these measurements to be made.

Assuming that a tooth 80 with a caries 88 on the crown 81 has to betreated, an anaesthetic is given and an aperture 95 of a diameter of mm2-4 is made in the crown 81 until the entrances 96 and 97 to the rootcanals 84 and 85 (FIG. 3) can be seen.

Said canals are then probed to calculate the necessary depth which mustcorrespond to the entire length of the canal less about 1 mm from itsapex.

By using the needle 100 already described it is possible to calculatethe length of intervention by electronic means.

For this purpose the push button 22 on the apparatus 10 is pressed andthe machine is set for measuring the root canal.

This setting is confirmed by illumination of the pilot light 23. Then,as seen in FIG. 5, the pincer 64 is applied to the lower lip 111 of thepatient 110, said pincer being on cable 65 connected to cable 62, afterwhich the needle 100 mounted in the handle 50 is introduced into theroot canal to which treatment has to be given, for example the canal 84(see FIG. 4).

When the tip 105 of said needle 100 reaches the beginning of the apicalarea, a two-tone warning sound is given.

This signal announces that the correct depth for devitalization has beenreached, namely the depth of about mm 1.5 from the apex.

At this point the operator removes the pincer from the lip of thepatient who than takes hold of the neutral handle 60 (FIG. 5) andpresses the button concerned with the treatment from among buttons 30-33on the apparatus.

When the right button has been pressed, the apparatus automatically setsthe time, power and frequency necessary and automatically passes fromthe setting for measuring depth to that for distributing energy. Theoperator then presses the control pedal 70 determining generation,inside the root canal in which the needle is lodged, of an electricpulse sufficient to devitalize said canal.

A single-tone warning signal indicates completion of the treatment.

Power of the current used for this purpose is substantially 70 W RF, at300 Ohm, high frequency of about 0.5 Mhz and is applied for about onetenth of a second.

After the operation the machine automatically returns to the “measuring”position ready to repeat the cycle.

The pulse of current emitted by the machine acts on the bundlecomprising nerves, vein and artery in the canal.

The bundle of nerves is disintegrated and blood in the vein iscoagulated at the same time.

Practically speaking the whole of the material in the canal is removedand the canal, as well as its branches (FIG. 4) is sterilized.

The operator then closes the canals with special cement 45 and can treatthe caries 88 and complete the filling 46 (FIG. 7).

The whole apparatus is electronically controlled as seen in the blockdiagram in FIG. 8,

This diagram comprises the entry filter 120, feeder 121, RF pulser,generator of pulse radio frequency 122, the circuit 123 for settingoutput power shown on the display 124, the circuit 125 for setting Bursttime, the circuit 126 for passage, by control 127, from manual toautomatic operation and vice versa, the circuit 128 that automaticallyprotects the output pulse so that it does not exceed the set power valueand the safety circuit 129 that prevents involuntary repetition of thedevitalizing process before 10 seconds have passed.

The circuit 130 is an acoustic warning whose two-tone signal warns whenthe apical point has been reached during measuring, and whose singletone sounds warns that the devitalizing pulse has been applied and theoperation completed.

When in its automatic setting the apparatus selects, by buttons 30-33the type of tooth to be treated and then automatically adjusts power andtime for that type of tooth.

Output power can be adjusted with button 24 that acts on the circuit131.

What is claimed is:
 1. A method of devitalizing a tooth, comprising thesteps of inserting in a root canal through an aperture extending to anentry of the root canal an electrode in form of a needle connected to anelectronic apparatus that generates both an acoustic and visual signalwhen a tip of the needle is close to an apical hole; generatinghigh-frequency electric pulses; providing a plurality of preset valuesof power, time and frequency according to a type of a tooth to betreated for selection by the user and selecting a preset value todestroy that part of a vascular nervous tissue in contact with theneedle and to coagulate a vascular bundle that has not been destroyed,so that when the tip of the needle is close to the apical hole, thehigh-frequency electric pulses are generated and transmitted to thetooth by an operator thereby devitalizing the tooth.
 2. A method asdefined in claim 1; and further comprising placing a socket for a cablethat connects an electronic circuit to a metal neutral handle, incontact with a part of a patient's body during a treatment to assisttransmission of the high frequency electric pulse to the vascularnervous tissue and the vascular bundle.
 3. A method as defined in claim1; and further comprising applying a pincer connected by a cable to asocket of the apparatus, to a part of a patient's face during measuring.4. A method as defined in claim 1; and further comprising producing anemission of the high-frequency pulse by a pedal control device.
 5. Amethod as defined in claim 1; and further comprising automaticallyadjusting the power, time and frequency of the high frequency electricpulse by the electronic apparatus by pressing one of push buttons whichcorresponds to a type of the tooth which is being treated.
 6. A methodas defined in claim 1; and further comprising increasing a value of thehigh-frequency pulse by a control placed on the apparatus.
 7. A methodas defined in claim 1; and further comprising using the needle composedof stainless steel.
 8. A method as defined in claim 1; and furthercomprising the step of using the needle which has a shaft with adiameter of substantially 1 mm, a rear section with a length ofsubstantially 15 mm, a front section with a length of substantially 5 mmand is bent at an angle of substantially 110° relative to the rearsection.
 9. A method as defined in claim 1; and further comprising usingthe needle which is selected from a set including needles of differentlength with an average length of substantially 30 mm, and also includingneedles of a tapering structure with a diameter at a base ofsubstantially 0.25 mm and at a tip of substantially 0.1 mm.
 10. A methodas defined in claim 1; and further comprising using the apparatus whichincludes a cable for electric feed, a cable for the high frequencyelectric pulse operated by a pedal, a socket for a cable connected to anactive handle of insulating material with a metal core with a head at afront end, into which the needle is insertable and fixable.
 11. Anequipment for executing a tooth devitalizing process, comprising anelectrode in form of a needle insertable into a root canal through anaperture extending to an entry of the root canal; means for generatingan acoustic and visual signal when a tip of said needle is close to anapical hole; means for generating high-frequency electric pulses; meansfor providing a plurality of preset values of power, time and frequencyaccording to a type of tooth being treated for selection by the user,and selecting a preset value to destroy a part of a vascular nervoustissue in contact with the needle and to coagulate a vascular bundlethat has not been destroyed, so that when said tip of said needle isclose to the apical hole, said high-frequency electric pulses aregenerated and transmitted to the tooth by an operator therebydevitalizing the tooth.
 12. An apparatus as defined in claim 11, whereinsaid apparatus includes input filters, a feeder, a pulser for generationof the high frequency electric pulse, a circuit for setting an outputpower, a circuit for visualizing power on a display, a circuit forsetting Burst time, a circuit for changing over from manual to automaticoperation and vice versa, a circuit for protection against an increasein a value set for output power, a safety circuit for preventing aninvoluntary repetition of a devitalizing operation before a set time haspassed, a circuit for a two-tone acoustic warning to be sounded whenduring a measuring stage a tip of the needle reaches an apical hole, anda signal-tone warning to indicate that the high frequency electric pulsehas taken effect and an operation has therefore been completed.